What is the immediate management for a patient presenting with ST elevation myocardial infarction (STEMI)?

Immediate Management of ST-Elevation Myocardial Infarction (STEMI)

Primary percutaneous coronary intervention (PCI) performed within 120 minutes of diagnosis is the preferred reperfusion strategy and should be initiated immediately with concurrent dual antiplatelet therapy (aspirin plus ticagrelor or prasugrel) and anticoagulation to reduce mortality and preserve myocardial function. 1

Initial Assessment and Stabilization

Obtain a 12-lead ECG within 10 minutes of first medical contact to confirm STEMI diagnosis (persistent ST-segment elevation or new left bundle branch block). 2

• Initiate continuous ECG monitoring with defibrillator capacity immediately upon patient contact 2
• Avoid routine oxygen therapy unless oxygen saturation is <90% 2
• Transfer patients directly to the catheterization laboratory, bypassing the emergency department entirely 1

Antiplatelet Therapy (Administer Immediately)

Give aspirin 150-325 mg orally (or 250-500 mg IV if unable to swallow) as soon as possible without delay. 1, 2

Administer a potent P2Y12 inhibitor before or at the time of PCI:

• Prasugrel 60 mg loading dose (preferred in most patients undergoing PCI), followed by 10 mg daily 1, 3
  • Reduce maintenance dose to 5 mg daily if body weight <60 kg 3
  • Avoid prasugrel in patients ≥75 years old (increased fatal bleeding risk), except in high-risk situations like diabetes or prior MI 3
  • Contraindicated in patients with prior stroke or TIA 3
• Ticagrelor 180 mg loading dose (alternative to prasugrel), followed by 90 mg twice daily 1, 2
• Clopidogrel only if prasugrel and ticagrelor are unavailable or contraindicated 1

Continue dual antiplatelet therapy (DAPT) for 12 months unless excessive bleeding risk exists. 1

Anticoagulation During PCI

Administer unfractionated heparin (UFH) as IV bolus:

• 100 U/kg if no GPIIb/IIIa inhibitors planned 2
• 60 U/kg if GPIIb/IIIa inhibitors will be used 2

Do not use fondaparinux for primary PCI (contraindicated in this setting). 1

Reperfusion Strategy Decision Algorithm

If Primary PCI Available Within 120 Minutes:

Proceed directly to primary PCI - this is the gold standard reperfusion approach. 1, 2

• PCI-capable centers must provide 24/7 service without delay 1
• Use radial access and drug-eluting stents as standard of care 2
• Avoid routine thrombus aspiration (not recommended) 2

If Primary PCI Cannot Be Performed Within 120 Minutes:

Initiate fibrinolytic therapy immediately, preferably in the pre-hospital setting. 1

Fibrinolytic regimen:

• Tenecteplase (preferred fibrin-specific agent): 30-50 mg (0.53 mg/kg) as single IV bolus 2
  • Reduce dose by 50% in patients ≥75 years old 2
• Alternative agents: alteplase or reteplase 1
• Give aspirin (oral or IV) 1
• Add clopidogrel 1
• Anticoagulation with enoxaparin IV followed by subcutaneous (preferred over UFH) or weight-adjusted UFH bolus plus infusion 1
• Continue anticoagulation until revascularization or up to 8 days of hospitalization 1

After fibrinolysis, transfer ALL patients to PCI-capable center immediately: 1

• Perform angiography and PCI of infarct-related artery between 2-24 hours after successful fibrinolysis 1
• Rescue PCI immediately if fibrinolysis fails (<50% ST-segment resolution at 60-90 minutes) or if hemodynamic/electrical instability develops 1

Special Circumstances

Cardiogenic shock or heart failure: Emergency angiography and PCI are mandatory regardless of time from symptom onset. 1

Cardiac arrest with post-resuscitation ST-elevation: Pursue primary PCI strategy. 2

Symptom onset >12 hours: Reperfusion therapy is indicated only if symptoms of ischemia persist with ST-elevation. 1

Critical Pitfalls to Avoid

• Never delay aspirin or P2Y12 inhibitor administration while arranging PCI - give these medications immediately upon STEMI diagnosis 1, 2
• Do not administer IV beta-blockers acutely in patients with hypotension, acute heart failure, AV block, or severe bradycardia (increases mortality) 1
• Do not perform PCI on non-infarct related arteries during the acute procedure unless the patient is in cardiogenic shock 2
• In STEMI patients presenting within 12 hours of symptom onset, prasugrel loading dose should be given at time of diagnosis, though most receive it at time of PCI 3
• For UA/NSTEMI patients, prasugrel should not be given until coronary anatomy is established to avoid bleeding risk if urgent CABG is needed 3

Additional Acute Therapies

Initiate high-intensity statin therapy as early as possible during hospitalization. 1, 2

Start oral beta-blockers only after stabilization in patients with heart failure or LVEF <40%, unless contraindicated. 1

Perform echocardiography during hospitalization to assess ventricular function, detect mechanical complications, and exclude LV thrombus. 1